Hibernate @ManyToMany映射給出異常

Question

所以我看到很多類似於這個問題，似乎沒有類似於我的雖然..所以我想了解Hibernate映射 - （困在ManyToMany）映射。

所以我想使3個表，其中有學生詳細信息，第二，提供的課程和第三存儲與相應的課程ID學生ID ...

下面是表...

public class Student implements Serializable 
{ 
/** 
* 
*/ 
private static final long serialVersionUID = 1L; 

@Id 
@GeneratedValue(strategy = GenerationType.IDENTITY) 
@Column(name="st_id") 
private Integer id; 

@Column(name="name") 
private String name; 

@ManyToMany(cascade = CascadeType.ALL) 
@JoinTable(name="StudentCourses", joinColumns = { @JoinColumn(name="st_id")}, inverseJoinColumns = { @JoinColumn(name="c_id")}) 
private HashSet<Course> courses = new HashSet<Course>(); 

// respective setter getters 
} 

第二類課程

public class Course implements Serializable 
{ 
/** 
* 
*/ 
private static final long serialVersionUID = 1L; 

@Id 
@GeneratedValue(strategy = GenerationType.IDENTITY) 
@Column(name="c_id") 
private Integer c_id; 

@Column(name="c_name") 
private String c_name; 

@Column(name="c_fee") 
private String c_fee; 

// respective setter and getters 
} 

現在，當我嘗試添加課程，它給了我下面的異常。 請讓我知道我要去哪裏錯了。

WARNING: Exception encountered during context initialization - cancelling refresh attempt: org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'generalDAO' defined in file [G:\Kaustubh\Training\HibernateMapping\target\classes\com\bluetree\DAOImpl\GeneralDAOImpl.class]: Unsatisfied dependency expressed through constructor parameter 0; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'sessionFactory' defined in com.bluetree.appConfig.ApplicationContextConfig: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.hibernate.SessionFactory]: Factory method 'getSessionFactory' threw exception; nested exception is org.hibernate.AnnotationException: Illegal attempt to map a non collection as a @OneToMany, @ManyToMany or @CollectionOfElements: com.bluetree.model.Student.courses 
Exception in thread "main" org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'generalDAO' defined in file [G:\Kaustubh\Training\HibernateMapping\target\classes\com\bluetree\DAOImpl\GeneralDAOImpl.class]: Unsatisfied dependency expressed through constructor parameter 0; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'sessionFactory' defined in com.bluetree.appConfig.ApplicationContextConfig: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.hibernate.SessionFactory]: Factory method 'getSessionFactory' threw exception; nested exception is org.hibernate.AnnotationException: Illegal attempt to map a non collection as a @OneToMany, @ManyToMany or @CollectionOfElements: com.bluetree.model.Student.courses 
    at org.springframework.beans.factory.support.ConstructorResolver.createArgumentArray(ConstructorResolver.java:749) 
    at org.springframework.beans.factory.support.ConstructorResolver.autowireConstructor(ConstructorResolver.java:189) 
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.autowireConstructor(AbstractAutowireCapableBeanFactory.java:1148) 
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1050) 
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:512) 
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:482) 
    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:306) 
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230) 
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:302) 
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:197) 
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:754) 
    at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:866) 
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:542) 
    at com.bluetree.test.TestMappings.<init>(TestMappings.java:25) 
    at com.bluetree.test.TestMappings.main(TestMappings.java:63) 
Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'sessionFactory' defined in com.bluetree.appConfig.ApplicationContextConfig: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.hibernate.SessionFactory]: Factory method 'getSessionFactory' threw exception; nested exception is org.hibernate.AnnotationException: Illegal attempt to map a non collection as a @OneToMany, @ManyToMany or @CollectionOfElements: com.bluetree.model.Student.courses 
    at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:599) 
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateUsingFactoryMethod(AbstractAutowireCapableBeanFactory.java:1128) 
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1022) 
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:512) 
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:482) 
    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:306) 
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230) 
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:302) 
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:202) 
    at org.springframework.beans.factory.config.DependencyDescriptor.resolveCandidate(DependencyDescriptor.java:207) 
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1131) 
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1059) 
    at org.springframework.beans.factory.support.ConstructorResolver.resolveAutowiredArgument(ConstructorResolver.java:835) 
    at org.springframework.beans.factory.support.ConstructorResolver.createArgumentArray(ConstructorResolver.java:741) 
    ... 14 more 
Caused by: org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.hibernate.SessionFactory]: Factory method 'getSessionFactory' threw exception; nested exception is org.hibernate.AnnotationException: Illegal attempt to map a non collection as a @OneToMany, @ManyToMany or @CollectionOfElements: com.bluetree.model.Student.courses 
    at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:189) 
    at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:588) 
    ... 27 more 
Caused by: org.hibernate.AnnotationException: Illegal attempt to map a non collection as a @OneToMany, @ManyToMany or @CollectionOfElements: com.bluetree.model.Student.courses 
    at org.hibernate.cfg.annotations.CollectionBinder.getCollectionBinder(CollectionBinder.java:324) 
    at org.hibernate.cfg.AnnotationBinder.processElementAnnotations(AnnotationBinder.java:1899) 
    at org.hibernate.cfg.AnnotationBinder.processIdPropertiesIfNotAlready(AnnotationBinder.java:913) 
    at org.hibernate.cfg.AnnotationBinder.bindClass(AnnotationBinder.java:740) 
    at org.hibernate.boot.model.source.internal.annotations.AnnotationMetadataSourceProcessorImpl.processEntityHierarchies(AnnotationMetadataSourceProcessorImpl.java:249) 
    at org.hibernate.boot.model.process.spi.MetadataBuildingProcess$1.processEntityHierarchies(MetadataBuildingProcess.java:222) 
    at org.hibernate.boot.model.process.spi.MetadataBuildingProcess.complete(MetadataBuildingProcess.java:265) 
    at org.hibernate.boot.model.process.spi.MetadataBuildingProcess.build(MetadataBuildingProcess.java:83) 
    at org.hibernate.boot.internal.MetadataBuilderImpl.build(MetadataBuilderImpl.java:418) 
    at org.hibernate.boot.internal.MetadataBuilderImpl.build(MetadataBuilderImpl.java:87) 
    at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:691) 
    at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:726) 
    at com.bluetree.appConfig.ApplicationContextConfig.getSessionFactory(ApplicationContextConfig.java:63) 
    at com.bluetree.appConfig.ApplicationContextConfig$$EnhancerBySpringCGLIB$$98c986dc.CGLIB$getSessionFactory$0(<generated>) 
    at com.bluetree.appConfig.ApplicationContextConfig$$EnhancerBySpringCGLIB$$98c986dc$$FastClassBySpringCGLIB$$e094f8d6.invoke(<generated>) 
    at org.springframework.cglib.proxy.MethodProxy.invokeSuper(MethodProxy.java:228) 
    at org.springframework.context.annotation.ConfigurationClassEnhancer$BeanMethodInterceptor.intercept(ConfigurationClassEnhancer.java:356) 
    at com.bluetree.appConfig.ApplicationContextConfig$$EnhancerBySpringCGLIB$$98c986dc.getSessionFactory(<generated>) 
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) 
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) 
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) 
    at java.lang.reflect.Method.invoke(Method.java:497) 
    at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:162) 
    ... 28 more 

幫助將不勝感激。謝謝。 這上面的代碼，我從以下Link

Answer 1

試圖嘗試過使用接口引用，而不是實現即

private Set<Course> courses = new HashSet<Course>();